Q

Traveling data during backup, Part II

Hi, Marc,

According to what you mentioned in the answer to the question posed on October 2, --> --> --> 1 "Traveling data during backup" ... serverless backup has the concept of data movers... requires a great deal of synchronization between host file systems and the backup system - including the data mover. The data mover can reside almost anywhere - including a switch. Someday..."

1. By saying "a great deal of synchronization," do you mean the serverless backup actually puts a different data format in the tape and that raw data (or block of data) requires some extra work in a recovery? Who do you consider the most sophisticated software vendor in severless backup?

2. By saying "data mover can reside almost anywhere - including a switch. Someday..." do you mean, now, that there are no hubs or switches residing in the SAN cloud that can act as data movers? If there is some do that, could you give examples?

Thanks a lot!

A loyal reader of your book,
Calvin


Thanks for the question, Calvin.

Synchronization has nothing to do with formats. It has everything to do with data that is updated while the backup is running. Look in my book for information on hot backups and copy on write. The problem is that you need a consistent image of the data, not data that potentially represents two different versions. Big, busy systems have lots to back up and they typically have a lot of activity. There is a lot of detailed bookkeeping and synchronization of functions to make sure that the data being moved by a data mover is being protected by a host-based copy on write process.

As to vendors and comparisons: I try not to do this because as soon as I do, I'll be wrong. Talk to the different vendors and ask them specific questions about their backup products, including how they handle hot backups of live data for serverless backup.

It?'s the same thing for vendors of SAN products. You will need to find out from them what the status is of any data mover implementations.

Regards,
Marc

Editor's note: To check out Marc's answer that Calvin is referring to, go to http://www.searchStorage.com/ateQuestionNResponse/0,289625,sid5_cid416435_tax286191,00.html or to take a look at Marc's book go to http://www.digitalguru.com/DigitalGuru/product_detail.asp?catalog_name=Books&category_name=∏uct_id=0072130725∂ner_id=69

Editor's note: Do you agree with this expert's response? If you have more to share, post it in our Storage Networking discussion forum at http://searchstorage.discussions.techtarget.com/WebX?replyToMessage@200.MullaECzaUO^1@.ee83ce4!viewtype=convdate or e-mail us directly at editor@searchstorage.com.


This was first published in October 2001

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